Conventionally, lumbar support assemblies are used for maintaining a seat cushion in a contoured position. Such lumbar support assemblies usually include either bellows, air bladder or a pump to force air into the cushion pocket to reach a desired contour.
British Patent Number 1,299,789 discloses an adjustable self inflated support cushion with an air impermeable exterior shell which surrounds an open self foamed material. Further, U.S. Pat. No. 4,516,568 to Baxter et al discloses yet another pressure exerting device comprising a resilient wedged shape member and modified U-shaped air bladder which may be filled to selected air pressures. However, these systems of lumbar adjustment are inadequate as they are sensitive to temperature change thus rendering adjustment hard to achieve. Moreover, foam tends disintegrate with wear over time, thus, decreasing contour effect. And none have a normal state with the bladder in the inflated state without air pressure being applied.